Alzheimer's disease (AD) is a progressive dementia, but a definite diagnosis of AD can only be established postmortem by demonstrating abundant senile plaques (SPs) and neurofibrillary tangles (NFTs) according to consensus criteria. However, other lesions contribute to dementia, while NFTs and SPs occur in the brains of normal subjects and patients with other nervous system disorders. Further, AD lesions and cortical Lewy bodies (Lbs) define the LB variant of AD (LBVAD), and AD is common in Parkinson's disease (PD). Additionally, an AD-like dementia occurs in neuropathologically confirmed frontotemporal dementia, dementia with Lbs (DLB), tauopathies, etc. Moreover, alpha- synuclein (AS) is the major component of Lbs in PD, LBVAD and DLB, while anti-AS antibodies detect Lbs in >50% of familial AD and Down's syndrome brains. Since understanding of AD and related dementias is evolving rapidly, accurate neuropathological diagnosis of post-mortem brains from subjects in the Clinical Core (Core B) of this ADCC continues to be a key function of this Neuropathology Core (Core C), which distributes samples of brains from AD and control subjects for research on AD or related disorders at and beyond the University of Pennsylvania Medical Center (UPMC). Further, Core C performs Apolipoprotein C (APOE) genotyping on Core B subjects, and banks cerebrospinal fluid and serum from Core B subjects for research within and outside UPMC. All information is entered into a confidential database, and data are provided to the National Alzheimer Coordinating Center (NACC). Thus, Core C performs critical functions in support of the Penn ADCC mission to increase the quality and quantity of AD research within and beyond UPMC.